KAZO, Japan — The ground started to buck at the Fukushima Daiichi nuclear power plant, and Masayuki Ishizawa could scarcely stay on his feet. Helmet in hand, he ran from a workers’ standby room outside the plant’s No. 3 reactor, near where he and a group of workers had been doing repair work. He saw a chimney and crane swaying like weeds. Everybody was shouting in a panic, he recalled.

Mr. Ishizawa, 55, raced to the plant’s central gate. But a security guard would not let him out of the complex. A long line of cars had formed at the gate, and some drivers were blaring their horns. “Show me your IDs,” Mr. Ishizawa remembered the guard saying, insisting that he follow the correct sign-out procedure. And where, the guard demanded, were his supervisors?

“What are you saying?” Mr. Ishizawa said he shouted at the guard. He looked over his shoulder and saw a dark shadow on the horizon, out at sea, he said. He shouted again: “Don’t you know a tsunami is coming?”

Mr. Ishizawa, who was finally allowed to leave, is not a nuclear specialist; he is not even an employee of the Tokyo Electric Power Company, the operator of the crippled plant. He is one of thousands of untrained, itinerant, temporary laborers who handle the bulk of the dangerous work at nuclear power plants here and in other countries, lured by the higher wages offered for working with radiation. Collectively, these contractors were exposed to levels of radiation about 16 times as high as the levels faced by Tokyo Electric employees last year, according to Japan’s Nuclear and Industrial Safety Agency, which regulates the industry. These workers remain vital to efforts to contain the nuclear crisis at the Fukushima nuclear plants.

They are emblematic of Japan’s two-tiered work force, with an elite class of highly paid employees at top companies and a subclass of laborers who work for less pay, have less job security and receive fewer benefits. Such labor practices have both endangered the health of these workers and undermined safety at Japan’s 55 nuclear reactors, critics charge.

“This is the hidden world of nuclear power,” said Yuko Fujita, a former physics professor at Keio University in Tokyo and a longtime campaigner for improved labor conditions in the nuclear industry. “Wherever there are hazardous conditions, these laborers are told to go. It is dangerous for them, and it is dangerous for nuclear safety.”

Photo

Workers refueled a portable power generator at the Fukushima Daiichi nuclear power plant last month.Credit
Nuclear and Industrial Safety Agency, via Kyodo News and Reuters

Of roughly 83,000 workers at Japan’s 18 commercial nuclear power plants, 88 percent were contract workers in the year that ended in March 2010, the nuclear agency said. At the Fukushima Daiichi plant, 89 percent of the 10,303 workers during that period were contractors. In Japan’s nuclear industry, the elite are operators like Tokyo Electric and the manufacturers that build and help maintain the plants like Toshiba and Hitachi. But under those companies are contractors, subcontractors and sub-subcontractors — with wages, benefits and protection against radiation dwindling with each step down the ladder.

Interviews with about a half-dozen past and current workers at Fukushima Daiichi and other plants paint a bleak picture of workers on the nuclear circuit: battling intense heat as they clean off radiation from the reactors’ drywells and spent-fuel pools using mops and rags, clearing the way for inspectors, technicians and Tokyo Electric employees, and working in the cold to fill drums with contaminated waste.

Some workers are hired from construction sites, and some are local farmers looking for extra income. Yet others are hired by local gangsters, according to a number of workers who did not want to give their names.

They spoke of the constant fear of getting fired, trying to hide injuries to avoid trouble for their employers, carrying skin-colored adhesive bandages to cover up cuts and bruises.

In the most dangerous places, current and former workers said, radiation levels would be so high that workers would take turns approaching a valve just to open it, turning it for a few seconds before a supervisor with a stopwatch ordered the job to be handed off to the next person. Similar work would be required at the Fukushima Daiichi plant now, where the three reactors in operation at the time of the earthquake shut down automatically, workers say.

“Your first priority is to avoid pan-ku,” said one current worker at the Fukushima Daini plant, using a Japanese expression based on the English word puncture. Workers use the term to describe their dosimeter, which measures radiation exposure, from reaching the daily cumulative limit of 50 millisieverts. “Once you reach the limit, there is no more work,” said the worker, who did not want to give his name for fear of being fired by his employer.

Takeshi Kawakami, 64, remembers climbing into the spent-fuel pool of the No. 1 reactor at the Fukushima Daiichi plant during an annual maintenance shutdown in the 1980s to scrub the walls clean of radiation with brushes and rags. All workers carried dosimeters set to sound an alarm if exposure levels hit a cumulative dose limit; Mr. Kawakami said he usually did not last 20 minutes.

“It was unbearable, and you had your mask on, and it was so tight,” Mr. Kawakami said. “I started feeling dizzy. I could not even see what I was doing. I thought I would drown in my own sweat.”

Since the mid-1970s, about 50 former workers have received workers’ compensation after developing leukemia and other forms of cancer. Health experts say that though many former workers are experiencing health problems that may be a result of their nuclear work, it is often difficult to prove a direct link. Mr. Kawakami has received a diagnosis of stomach and intestinal cancer.

News of workers’ mishaps turns up periodically in safety reports: one submitted by Tokyo Electric to the government of Fukushima Prefecture in October 2010 outlines an accident during which a contract worker who had been wiping down a turbine building was exposed to harmful levels of radiation after accidentally using one of the towels on his face. In response, the company said in the report that it would provide special towels for workers to wipe their sweat.

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Most day workers were evacuated from Fukushima Daiichi after the March 11 earthquake and tsunami, which knocked out the plant’s power and pushed some of the reactors to the brink of a partial meltdown. Since then, those who have returned have been strictly shielded from the news media; many of them are housed at a staging ground for workers that is off limits to reporters. But there have been signs that such laborers continue to play a big role at the crippled power plant.

The two workers who were injured two weeks ago when they stepped in radioactive water were subcontractor employees. As of Thursday, 21 workers at the plant had each been exposed to cumulative radiation levels of more than 100 millisieverts, or the usual limit set for nuclear plant workers during an emergency, according to Tokyo Electric. (That limit was raised to 250 millisieverts last month.)

The company refused to say how many contract workers had been exposed to radiation. Of roughly 300 workers left at the plant on Thursday, 45 were employed by contractors, the company said.

Day laborers are being lured back to the plant by wages that have increased along with the risks of working there. Mr. Ishizawa, whose home is about a mile from the plant and who evacuated with the town’s other residents the day after the quake, said he had been called last week by a former employer who offered daily wages of about $350 for just two hours of work at the Fukushima Daiichi plant — more than twice his previous pay. Some of the former members of his team have been offered nearly $1,000 a day. Offers have fluctuated depending on the progress at the plant and the perceived radiation risks that day. So far, Mr. Ishizawa has refused to return.

Photo

Masayuki Ishizawa had a close call as a nuclear worker.Credit
Moshe Komata/The New York Times

Working conditions have improved over the years, experts say. While exposure per worker dropped in the 1990s as safety standards improved, government statistics show, the rates have been rising since 2000, partly because there have been more accidents as reactors age. Moreover, the number of workers in the industry has risen, as the same tasks are carried out by more employees to reduce individual exposure levels.

Tetsuen Nakajima, chief priest of the 1,200-year-old Myotsuji Temple in the city of Obama near the Sea of Japan, has campaigned for workers’ rights since the 1970s, when the local utility started building reactors along the coast; today there are 15 of them. In the early 1980s, he helped found the country’s first union for day workers at nuclear plants.

The union, he said, made 19 demands of plant operators, including urging operators not to forge radiation exposure records and not to force workers to lie to government inspectors about safety procedures. Although more than 180 workers belonged to the union at its peak, its leaders were soon visited by thugs who kicked down their doors and threatened to harm their families, he said.

“They were not allowed to speak up,” Mr. Nakajima said. “Once you enter a nuclear power plant, everything’s a secret.”

Last week, conversations among Fukushima Daiichi workers at a smoking area at the evacuees’ center focused on whether to stay or go back to the plant. Some said construction jobs still seemed safer, if they could be found. “You can see a hole in the ground, but you can’t see radiation,” one worker said.

Mr. Ishizawa, the only one who allowed his name to be used, said, “I might go back to a nuclear plant one day, but I’d have to be starving.” In addition to his jobs at Daiichi, he has worked at thermal power plants and on highway construction sites in the region. For now, he said, he will stay away from the nuclear industry.

“I need a job,” he said, “but I need a safe job.”

A version of this article appears in print on April 10, 2011, on Page A1 of the New York edition with the headline: Braving Heat And Radiation For Temp Job. Order Reprints|Today's Paper|Subscribe